Packers are generally utilized in wellbore operations to provide a seal (e.g., annular seal) or barrier to fluid flow across an annulus formed between an inner tubular member and the wall of the wellbore (e.g., borehole, well). Packers may be used in open hole operations, wherein the portion of the wellbore in which the packer is set has not been completed, e.g., it has not been cased; as well as completed portions of the wellbore which are cased (e.g., casing, liner, etc.). In some operations, the packer includes a sealing portion, typically an elastomer portion, which is expanded radially out from the mandrel to engage the wellbore wall to form the barrier.
The elastomer ring may be expanded radially in various manners including mechanical manipulation (e.g., rotation), inflation, and by compressing the elastomer portion. The force to compress the elastomer ring is commonly provided by hydraulic pressure and/or by weight. The wellbore operation being performed will often dictate the preferred type of packer, e.g., inflatable, hydraulically set, weight set, etc.; and may dictate whether the packer is retrievable or permanent.
One example of a wellbore operation in which one or more packers is utilized is in wellbore testing operations, for example drillstem testing (“DST”). For example, for the purpose of measuring a characteristic of the well (e.g., formation pressure, flow rates, etc.) of a subterranean formation, a tubular test string may be dispose in the wellbore that extends into the formation. In order to test a particular region, or zone, of the formation the test string may include a perforating gun that is used to form perforation tunnels, or fractures, into the formation surrounding the wellbore and perforations through the casing. To isolate the test zone, for example from the surface of the well, the test string may carry a packer to be set at the desired location in the well.
Examples of packer and packer systems that may be utilized, for example, for well testing are disclosed in U.S. Pat. Nos. 6,186,227, 6,315,050, and 6,564,876, all of which are incorporated herein by reference. There is a continued desired to provide reliable, robust, wellbore packers and packer systems.